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Samples may be delivered to Twining's chemistry laboratory in Fresno, California. The Twining <br />representative in charge of the field work transport or direct the transportation of the samples and <br />custody forms to the laboratory, where the samples are transferred to the sample control department. <br />A receiving clerk, or an authorized analyst, signs the custody forms, present a duplicate copy to the <br />Twining representative, and transfers the samples to a laboratory analyst. The condition of the <br />custody seal will be annotated on the custody form in the "remarks" section. The laboratory manager <br />retains possession of the custody forms during analyses of the samples. <br />The laboratory manager's responsibilities include monitoring the sample integrity within the <br />laboratory. This involves assigning each sample a laboratory number and maintaining cross- <br />reference between the sample's field and laboratory identifications. The analysts' responsibilities <br />include maintaining accurate records of the samples analyzed along with the analytical data <br />produced. This involves labeling chromatograms and maintaining the laboratory numbers on <br />subsamples taken from the submitted samples, labeling glassware used in the analyses, and properly <br />labeling sample extract containers with each sample's laboratory number. <br />Following analyses, the samples are transferred to a limited-access storage room. Chain-of-custody <br />forms, chromatograms, and other pertinent information are filed for future reference. Splits of <br />samples analyzed are kept for 30 days. Samples containing hazardous concentrations will be <br />returned to the client for disposal. <br />Laboratory Quality Assurance/Quality Control (QA/QC) : These laboratory QA/QC procedures <br />were developed to reduce outside interferences during analyses of samples. The laboratory director <br />is responsible for creating and maintaining the program. General QA/QC procedures follow: <br />Analytical instruments are serviced on a regular basis to assure accurate calibration; <br />Organic-free water is monitored daily for quality; <br />Gas chromatographs are calibrated daily; <br />Method blanks are run to check whether the glassware and reagents are free of <br />interference from chemicals that would invalidate the analyses; <br />Standards are prepared using the applicable reference materials; <br />Matrix spikes are analyzed in duplicate to validate the accuracy and precision of the <br />method; and <br />During groundwater sampling, a travel blank sample consisting o f organic-free water <br />is prepared and containerized in the laboratory, transported to the site, and handled <br />and transported in the same manner as the groundwater samples.